certain stores tend to congregate. Pet stores are a good example.
On Hong Kong Island, Cannon Street in Causeway
Bay is a "pet street". In Kowloon, Victory Avenue in Ho Man Tin district is
such a street.
On Victory Avenue, you can find pet store after pet store, and
there are at least two veterinarian clinics there at the time
of writing (2006.9.25).
you're looking for birdfeed and bird supplies, the "Mongkok
bird park" is the place to go. There you can find fresh snacks for birds - grasshoppers, grasshoppers, live!
For fish and aquarium
supplies, the "Mongkok
goldfish street" has all that you need and don't need.